CodePen Todo list debug

I am doing a front-end dev practice.

Here is my codepen project(https://codepen.io/Riederlee/pen/wQPrJo) In this project, there are two sections:

First part: there will be a todolist example which you can add some items.

Second part: I created a 2x2 table by using React. It turns out that the table cannot be seen on the screen so there must be something wrong.

I have a really hard time in finding bugs :(